EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: pinipon on September 09, 2014, 11:52:59 pm
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Hi guys,
I'm newbie in EEVblog forum. I would like to have your feedback about my "Chinese" power supply.
I bought this stuff 1 month ago and I decided to check some parameters/specs of the device:
Although the precision in DC is enough to me, on the adjustable output I can measure 80Vac rms between +/GND and same between -/GND. On the 5VDC fixed output I can measure 50Vac rms. Both 50Hz...
My question is: is that stuff safe or not?? or is an issue of the manufacturer... Do I have to claim to the store where I bought this stuff?
Please see the pictures at: https://www.dropbox.com/sh/ur99hk7cr8j6kds/AABXGCBb7qvm_AcoeBZFekFYa?dl=0 (https://www.dropbox.com/sh/ur99hk7cr8j6kds/AABXGCBb7qvm_AcoeBZFekFYa?dl=0)
Thanks in advance for your help.
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That's normal.
What matters is, how much AC current? It's dangerous if it's more than 5mA or so (under 1mA would be preferable).
Tim
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put a 1K resistor in parallel with your meter and retry. I can get tens of volts off house walls if i use my meter with about 1Gohm input resistance
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Either coupling from the transformer, or a cap across the transformer for RFI?, and probably very low current. I thought it in series halved the voltage however, but 80*2 seems like an odd voltage.
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80*2 seems like an odd voltage.
Input impedance.
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I put 1k resistor between - and GND and take only 40mV rms, current below 0.05mA that's the minimum the meter can measure. Same between + and GND.
I do same tests with my home made power supply with initially I take 16Vac rms, but putting a load make the voltage drop to an insignificant value.
Thanks guys for your help.
Cheers,
Pinipon
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if you just touch your meter probe you can pick up well more than 40mV from thin air ;)